Investigation of blood coagulation and hemophilia with a study of the hemophilias in dogs and von Willebrand disease in dogs and swine from genetic, biochemical and pathologic points of view, and the study of some of platelets with plasma proteins in the development of platelet adhesion and aggregation. Specific areas of investigation include studies of: a) genetics and pathophysiology of canine hemophilia A; b) study of animal von Willebrand disease ad a platelet aggregating factor in porcine plasma which is deficient in porcine von Willebrand disease; c) studies on dogs with multiple inherited deficiencies in plasma procoagulants; d) purification of von Willebrand factor and its administration to von Willebrand subjects; and e) role of plasma proteins in platelet adhesion and aggregation in the interfacial reaction between solids and blood (thrombogenic membranes).